Multi-stake vacuum pump



Dec. 4, 1962 A. LORENZ 3,066,855

' MULTI-STAGE VACUUM PUMP Filed May 15, 1959 5 Sheets-Sheet 1 Dec. 4, 1962 A. LORENZ 3,066,855

MULTI-STAGE VACUUM PUMP Filed May 15, 1959 5 Sheets-Sheet 2 Fig 3 Fig. 2

Dec. 4, 1962 A. LORENZ 3,066,855

MULTI-STAGE VACUUM PUMP Filed May 15, 1959 5 Sheets-Sheet 3 Fig- 4' Dec. 4, 1962 A. LORENZ 3,066,855

MULTI-STAGE VACUUM PUMP Filed May 15, 1959 5 Sheets-Sheet 4 Dec. 4, 1962 A. LORENZ 3,056,855

MULTI-STAGE VACUUM PUMP Filed May 15, 1959 5 Sheets-Sheet 5 Fig. 6

3,tldh,855

Patented Dec. 4, l92

3,066,855 MUL'Ill-STAKE VACUUM PUB/l? Albert Lorenz, Hanan (Main), Germany, assignor to W. C.

Heraeus, G.m.b.H., Hanan (Main), Germany, a corporation of Germany Filed May 15, 31959, Ser. No. 813,417 Claims priority, application Germany May 21, 1958 8 Qlaims. (Cl. 230-205) The present invention relates to improvements in multipie-stage vacuum pumps of the type in which a common housing contains several chambers which are separated from each other by partitions and in which separate gas conveying means forming the different stages of the pump are mechanically driven and sealed as well as lubricated by means of oil supplied from separate oil chambers.

In the known pumps of this type, the mechanical features of which are generally described, for example, in the US. patent to Kinney, No. 1,061,181, each of these oil chambers is provided with at least one oil-drain plug which is screwed into the respective drain opening. Such an arrangement in a multiple-stage pump has, however, the considerable disadvantage that, since there is a plurality of such drain plugs, it can easily happen that, when an oil change is required, one or more drain plugs will be overlooked and remain closed so that a part of the used oil will remain in the pump. Furthermore, the requirement for several oil drain plugs often leads to diiiiculties in designing the pump and in finding a suitable location for them in the pump housing.

It is an object of the present invention to provide a multiple-stage vacuum pump which eliminates the abovementioned disadvantages by designing the pump so that the drain openings of all the oil chambers are disposed in one row and are adapted to be closed by a single device. Consequently, when the pump has to be drained of its oil, no more than one closing device has to be opened. It is thus no longer possible that the operator of the pump might overlook one of the drain openings, and thus fail to drain the oil completely. The new pump design has the further advantage that the single draining device may be provided at a point which is very convenient for collecting the used oil. By this new design it is also no longer necessary to provide several containers for collecting the drained oil, which is often a difiicult procedure in view of the confined arrangement in which such vacuum apparatus are frequently installed.

According to one preferred embodiment of the invention, the oil drain openings of all the oil supply chambers are arranged behind each other in the same axial direction and all of these openings are adapted to be opened or closed by a single operation and by means of a single drain plug of a special design.

The oil chambers are preferably designed so that, when the drain plug is opened, they will be in direct communication with each other through the dilferent drain openings. The oil may thus drain simultaneously from all chambers and it will not dam up or become clogged in any part of the oil chambers.

The drain plug according to the invention preferably consists of a boltlike member which is screwed into at least one drain opening and is provided with sealing surfaces which will tightly fit into the different drain openings of the oil chambers and seal the latter relative to each other as well as toward the outside. This boltlike drain plug may be very easily inserted and tightened and just as easily removed from the drain openings to carry out the draining operation.

According to another embodiment of the invention, the boltlike drain plug may be designed so as also to serve as an oil outlet which may, either directly or through one or more shutoff valves, be connected to a suitable apparatus for regenerating the used oil. The oil may thus be drained from any particular oil chamber, be regenerated and then returned into another oil chamber. Alternately, the oil may also be drained completely from all the oil chambers either through the drain plug or in the same manner as previously described by the removal of the plug. The return of the regenerated oil may be carried out either through a suitable conduit in the drain plug itself or through a separate return conduit and one or more separate filling openings in the pump housing.

Thus, for example, the boltlike drain plug which is inserted into the oil drain openings may be provided with an outlet conduit or channel which communicates with the oil chamber of the pump stage which is connected to the atmosphere, and with a second conduit or channel which leads to the oil chamber of the pump stage at the vacuum side of the pump. The oil may thus be circulated continuously, the used oil being drawn off the oil chamber of the second stage, passed through the oil regenerator and returned into the oil chamber of the first stage. The oil regenerator may, for example, consist of a suitable oil filter, and an oil pump may be interposed in the conduit leading from the oil outlet channel of the drain plug to the regenerator so as to draw off the used oil and pass it in a continuous forced circulation through the oil filter and then back through the inlet channel of the drain plug to the other oil chamber.

Since in many cases the impurities in the pump oil are caused by condensed water, it is advisable to connect the lower end of the housing of the oil filter with a suitable apparatus in which the water is separated from the oil and discharged, while the purified oil is returned to the vacuum pump.

in order to facilitate and improve the operation of filling the vacuum pump with new oil or refilling it with the regenerated oil in a similar manner as the operation of draining the used oil from the pump, it is preferable to provide the oil chambers not only with drain openings but also, separately therefrom, with oil inlet openings which are likewise disposed in a straight line relative to each other and are adapted to be opened and closed by a common boltlike filling plug. The oil chambers of the different stages of the vacuum pump are preferably at least partly disposed above each other, and the oil inlet openings of the different oil chambers extend coaxially to each other and either vertically or obliquely. A specified amount of new or regenerated oil as required for the proper operation of the vacuum pump may thus be filled into a single inlet opening in the outer Wall of the pump housing, and it will then automatically be distributed in the proper ratio to the individual oil chambers of the different pump stages. Such automatic distribution of the new oil between the diiferent oil chambers will be insured particularly if these chambers directly communicate wtih each other through their individual inlet openings when the main inlet is opened. Although the filling plug may be in the form of a simple bolt, preferably with a conical. tip to fit tightly into a conical inlet opening of the oil chamber of the first or vacuum stage and with screw threads on its shaft to be secured in the threaded main inlet opening leading to the oil chamber of the second stage, it may also be provided with a bore or channel which preferably terminates into the oil chamber of the vacuum stage and may be connected by a suitable conduit at the outside of the pump housing to the oil regenerator.

These and other objects, features, and advantages of the present invention will become further apparent from the following detailed description thereof, particularly when read with reference to the accompanying drawings,

in which FIGURE 1 shows a longitudinal section of a twostage vacuum pump according to the invention;

FEGURE 2 shows a cross section taken along line A-A of FIGURE .1;

FIGURE 3 shows B-B of FIGURE 1;

FIGURE 4 shows CC of F-l-GURE 1;

FIGURE 5 shows a sectional view similar to a part of FIGURE 1 but illustrating a modification of the invention in which the draining device is connected to an oilregenerating apparatus, shown diagrammatically; while FIGURE 6 shows a sectional view similar to FLGURE 1 but illustrating another modification of the invention in which the draining device is likewise connected to an oilregeneratng apparatus, shown diagrammatically.

Referring to the drawings, the vacuum pump illustrated in FIGURES 1 to 4 is a two-stage pump of a type known as such, the mechanical features of which are similar to those of the pump described, for example, in the abovementioned patent to Kinney, No. 1,661,181. Both stages I and II of the pump are operated by a common shaft 1 which carries a pair of eccentrics 2 and 3 and through these eccentrics drives a pair of annular pistons and 5 in separate piston chambers 6 and 7. Piston chamber 6 of the first stage 1 of the pump at the vacuum side thereof is connected by one or more outlet channels 8 to an oil chamber 9 containing a certain supply of oil and disposed above piston chamber 6. This oil chamber 9 of stage I is connected by a channel lit? with the inlet chamber 11 of stage If and through the latter with piston chamher 7 of this stage. The air or gases entering through the main inlet 12 and conveyed by piston 4 through channel 8 pass through the oil in chamber 9 and then through channel ltl into inlet chamber 11, and thereby take along a certain amount of oil from chamber into chamber 11 and then into piston chamber 7 of stage II.

Apart from the oil chamber 8 of stage I, the pump housing contains a separate oil chamber 13 which is associated with the second stage II of the pump and is likewise disposed above the piston chamber 7 of stage IT. This piston chamber 7 is, however, closed toward oil chamber 13 by an outlet valve 14 which is lifted from its seat only by the pressure of the air or gases which are expelled from piston chamber 7. The partition 15 separating the two oil chambers El and 13 further contains a relief pressure valve 16 which is lifted from its seat only if a high excess pressure occurs in oil chamber 9, for example, at the beginning of the pumping operation. At all other times, valve 16 seals the two oil chambers 9 and 13 tightly relative to each other.

For draining the used, contaminated oil from oil chambers 9' and 1'13, the latter are provided with drain openings l7 and 18, respectively, which according to the invention are disposed coaxially to each other. Drain opening 17 of oil chamber 9 terminates into a drain channel 1% which also communicates with oil chamber 13 through apertures it? in a partition 21 of the pump housing, and extends through the outer wall 22 of the housing toward the outside. in the particular embodiment of the invention, as shown in FIGURES 1 to 4, drain opening 17 of oil chamber of stage i is made of a conical shape, while drain opening 18 is provided with inner screw threads. For closing both drain openings 17 and 18 simultaneously and sealing them tightly relative to each other as well as toward the outside, a drain plug 23 is used which has a boltlilce shape and is provided at its free end with a conical tip 24 and on its rear end adjacent to its head 25 with screw threads 26. This drain plug is inserted into drain opening is, drain channel 19, and the conical drain opening 17, and when a cross section taken along line a cross section taken along line i screwed tightly into the outer wall 22, its conical tip 24 will firmly seal the conical drain opening 17 of oil chamber 9, while its threaded portion in cooperation with the head 25 and a washer 27 will tightly seal the drain opening 18 of oil chamber 13.

if drain plug 23 is unscrewed from drain opening 18, the conical tip 24 is also withdrawn from drain opening 17 and both oil chambers 9 and i3 communicate with each other directly through drain opening 17, drain channel 1.9, and apertures 21; so that all the oil contained'in both oil chambers and 13 can drain out.

A specified amount of new oil may be filled into the pump through the main inlet 12, in which event it will iiow through piston chamber 6 into oil chamber 9 of stage I and then through channel it] and piston chamber 7 into oil chamber 13 of stage II. This manner of inserting the oil is, however, inadvisable for various reasons and it is preferably carried out more directly through a special oil inlet consisting of a threaded inlet opening 23 in the upper wall 29 of the housing and a further inlet opening 3% of a conical shape in the partition 15 between oil chambers it and 13. The two oil inlet openings 28 and 369 are disposed in the same axial direction above each other, and a bolt 31 with a conical tip 32 is inserted therein. When this filling bolt 31, which is preferably provided with a washer 33 underneath its head 34, is tightened, the conical tip 32 tightly seals the inlet opening 36, while the upper threaded part of bolt 31 in cooperation with washer 33 and head 34 tightly seals the inlet opening 28. Thus, by the single bolt 31, both oil chambers 9 and 13 are sealed tightly relative to each other as well as toward the outside.

For filling the new oil into the pump, the filling bolt 31 is unscrewed from inlet opening 28 so that the two oil chambers 9 and 13 communicate with each other through the inlet opening 30. When the new oil is then inserted through inlet opening 28, it first passes into oil chamber 13 of stage II and then also through inlet opening 36 into oil chamber 9 of stage I until, when the entire required amount of oil is filled in, a balance of oil will occur through inlet opening 30 and both stages I and II will contain the amount of oil required therein.

According to the modification of the invention as illustrated diagrammatically in FIGURE 5, the drain openings l7 and 18 are sealed by a drain plug of a special construction which is connected to an apparatus for regenerating the used oil. For this purpose, the boltlike drain plug 35 which is screwed into the outer wall 22 of the housing is provided with a central bore 36 which extends through the entire shaft 37 of plug 35 and the head 38 and continues outwardly thereof with a tubular extension 39 forming an inlet. This bore 36 terminates into oil chamber 9 of stage I. The shaft 37 of plug 35 is further provided with channel 4-0 separate from bore 36, which may, for example, be cylindrical and extend from its closed forward end through shaft 37 and terminate into a chamber 41 in head 38 which is provided with an outlet 42. The outer wall of channel 41} has a plurality of apertures 43 through which the oil drained from oil chamber 13 through the apertures 26 in partition 21 and drain channel 19 will pass into and through channel at), and chamber 41 to outlet 42. This outlet 42 is connected by a conduit 44 to an oil pump 45, for example, a gear pump, which in turn is connected to an oil regenerator 46. Oil pump 4-5 continuously draws the used oil from the lower part of oil chamber 13 of stage II of the vacuum pump and passes it to the regenerator 46 which may consist, for example, of an oil filter 47. After passing through the regenerator 46, the purified oil flows through a conduit 4;; to inlet 39 and through bore 36 in drain plug 35 into oil chamber 9 of stage I.

The oil regenerator as is preferably connected to a separator in which the condensed water and coarser im purities are removed before the oil is returned to the vacuum pump. The inlet 39 and outlet 42 may also be provided with shutofi valves, not shown.

According to the further modification of the invention, as illustrated in FIGURE 6, the filling bolt 50 has a central bore 51 which extends through the entire bolt and terminates into oil chamber 9 of stage I. It is connected to the return conduit 48 of regenerator 46 and thus serves for the same purpose as bore 36 in FIGURE 5, namely, to return the regenerated oil into oil chamber 9. Drain plug 52 has in this case only a single socket bore 53 which is similar in function to channel 40 in FIGURE 2 and also connected through apertures 54 in the wall of shaft 55 with drain channel 19 and through the latter and apertures 20 in the partition 21 with oil chamber 13 of stage II. The used oil is thus withdrawn continuously by pump 45 from the lower part of oil chamber 13 and after being regenerated in regenerator 46 it is passed through conduit 48 and bore 51 in filling bolt 50 back into oil chamber 9 of stage I. The balance of oil in stages I and II then proceeds from chamber 9 of stage I through channel 10 and inlet chamber 11 of stage II and then through outlet valve 14 to oil chamber 13. There will thus be a continuous circulation of oil within the pump, the used oil being withdrawn from oil chamber 13 of stage II and passed through the filling screw 50 into oil chamber 9 of stage I. If the oil is to be drained completely from both chambers 9 and 13, drain plug 52 is removed completely so that the oil can flow out through drain opening 17 from oil chamber 6 and through drain apertures 21) and drain opening 18 from oil chamber 13.

Although my invention has been illustrated and described with reference to the preferred embodiments thereof, I wish to have it understood that it is in no way limited to the details of such embodiments, but is capable of numerous modifications within the scope of the appended claims.

Having thus fully described my invention, what I claim is:

1. In a multiple-stage vacuum pump having a common housing with a plurality of separate pump chambers therein, mechanical pumping means in each of said chambers forming the difierent stages of said pump, a separate oil chamber in direct communication with and positioned on the pressure side of each of said pump chambers, respectively, each of said oil chambers having at least one drain opening, said drain openings of all of said oil chambers being disposed within one straight line, and a single member mounted on the housing and cooperable with said drain openings for simultaneously opening and closing all of said drain openings toward the outside.

2. A multiple-stage pump as defined in claim 1, wherein said drain openings of all of said oil chambers are disposed coaXially to each other, said single member forming a boltlike drain plug adapted to be inserted into all of said drain openings to close the same.

3. A multiple-stage pump as defined in claim 1, wherein, when said single member is opened, said oil chambers communicate directly with each other.

4. A multiple-stage pump as defined in claim 2, wherein said boltlike drain plug is screw-threaded and adapted to be screwed into at least one of said drain openings.

5. A multiple-stage pump as defined in claim 2, wherein said boltlike drain plug is provided with a plurality of sealing surfaces adapted to engage into said drain openings to close the same.

6. In a multiple-stage pump having a common housing with a plurality of separate pump chambers therein, mechanical pumping means in each of said chambers forming the different stages of the pump, a separate oil chamber associated with each of said pump chambers, each of said oil chambers having at least one drain opening, said drain openings of all of said oil chambers being disposed within one straight line, a single member mounted on the housing and cooperable with said drain openings for opening and closing said drain openings toward the outside, each of said oil chambers having at least one oil inlet opening separate from said drain opening, said inlet openings of all of said oil chambers being disposed within one straight line, and a single member mounted on the housing and cooperable with said inlet openings for opening and closing all of said inlet openings.

7. A multiple-stage pump as defined in claim 6, wherein said oil chambers are at least partly disposed above each other and said inlet openings are disposed coaxially to each other, said single inlet closing member forming a boltlike member extending in a downward direction into said housing.

8. A multiple-stage pump as defined in claim 6, wherein when said single inlet closing member is: opened, said oil chambers communicate directly with each other through said inlet openings.

References Cited in the file of this patent UNITED STATES PATENTS 1,020,774 Nilson Mar. 19, 1912 1,379,259 Hans May 24-, 1921 1,721,614 Carrier July 23, 1929 2,076,935 Burckhalter Apr. 13, 1937 2,215,256 Stoltz Sept. 17, 1940 2,263,296 Grise Nov. 18, 1941 2,628,770 Bowering Feb. 17, 1953 FOREIGN PATENTS 1,127,552 France Aug. 13, 1956 

